Tables work differently; sometimes counter-intuitively.
The solution is to use width
on the table cells instead of max-width
.
Although it may sound like in that case the cells won't shrink below the given width, they will actually.
with no restrictions on c, if you give the table a width of 70px, the widths of a, b and c will come out as 16, 42 and 12 pixels, respectively.
With a table width of 400 pixels, they behave like you say you expect in your grid above.
Only when you try to give the table too small a size (smaller than a.min+b.min+the content of C) will it fail: then the table itself will be wider than specified.
I made a snippet based on your fiddle, in which I removed all the borders and paddings and border-spacing, so you can measure the widths more accurately.
table {_x000D_
width: 70px;_x000D_
}_x000D_
_x000D_
table, tbody, tr, td {_x000D_
margin: 0;_x000D_
padding: 0;_x000D_
border: 0;_x000D_
border-spacing: 0;_x000D_
}_x000D_
_x000D_
.a, .c {_x000D_
background-color: red;_x000D_
}_x000D_
_x000D_
.b {_x000D_
background-color: #F77;_x000D_
}_x000D_
_x000D_
.a {_x000D_
min-width: 10px;_x000D_
width: 20px;_x000D_
max-width: 20px;_x000D_
}_x000D_
_x000D_
.b {_x000D_
min-width: 40px;_x000D_
width: 45px;_x000D_
max-width: 45px;_x000D_
}_x000D_
_x000D_
.c {}
_x000D_
<table>_x000D_
<tr>_x000D_
<td class="a">A</td>_x000D_
<td class="b">B</td>_x000D_
<td class="c">C</td>_x000D_
</tr>_x000D_
</table>
_x000D_